* Modules/fetch/FetchRequest.cpp:
(WebCore::buildOptions):
(WebCore::FetchRequest::initializeOptions):
* Modules/fetch/FetchRequest.h:
Switch to using the integrity metadata on the fetchOptions, removing the need to
store them directly on the internal request.

* loader/DocumentThreadableLoader.cpp:
(WebCore::DocumentThreadableLoader::DocumentThreadableLoader):
(WebCore::DocumentThreadableLoader::didReceiveResponse):
(WebCore::DocumentThreadableLoader::didReceiveData):
(WebCore::DocumentThreadableLoader::didFinishLoading):
(WebCore::DocumentThreadableLoader::loadRequest):
(WebCore::DocumentThreadableLoader::reportIntegrityMetadataError):
* loader/DocumentThreadableLoader.h:
Add a new flag, m_delayCallbacksForIntegrityCheck, which is used when integrity metadata
is present, so we can implement the 'wait' concept from the fetch spec, and delay informing
the clients until we have validated the integrity metadata.